The meter is used as a unit to measure medium distances or lengths.
It's a standard measure for short distances (up to 1 km long), in real estate and construction, supply materials, vehicle and aircraft dimensions, short geographical distances and directions in most countries excluding the USA where foot and yard are still widely used for this purpose.
The meter is widely used in most countries and is the official unit for medium lengths and distances (for example, road signs in continental Europe show maximum vehicle hight in meters). Primary exceptions are the United States of America, and some countries where feet and yards are used in limited extent: the United Kingdom and Canada, where the yard remains in limited use as a part of imperial system (for example, yards are used on road signs for shorter distances in the United Kingdom and feet are widely used in construction and real estate in Canada).

Definition of the Unit:

The meter (metre in UK spelling) is a unit of length/distance in the metric system (SI Unit system) equivalent to the length of the path travelled by light during a time interval of 1/299,792,458 of a second (in vacuum, defined since 1983).

As a result of the French Revolution in 1789, the old units of measure that were associated with the monarchy were replaced by the new units. The new unit of length was introduced which became known as the meter. In 1795 the meter was defined as 1/10,000,000 part of the quarter of a meridian, passing through Paris. The meter gained popularity in continental Europe during the nineteenth century, particularly in scientific field, and was officially adopted as an international measurement unit in 1875.
In 1960 the meter was defined as 1,650,763.73 wavelengths of light from a specified transition in krypton-86.
In 1983 the final definition of meter was accepted as length of the path travelled by light in a vacuum in 1/299,792,458 of a second.

Where it's used:

The meter is commonly used in different trades and industries (for examle in machinery manufacturing), on road signs to indicate vehicle hight limits, the distance to short travel to a given location (for example in automotive GPS navigation voice prompts), on maps to indicate small scale, for vehicle, vessels and aircragt dimensions in industry and trade. It is also the most popular unit for describing the retail estate distances and measurements (room sizes, floor measurements and so on).

The meter is a unit of length in the metric SI system and is equivalent to the length of the path travelled by light during a time interval of 1/299,792,458 of a second (in vacuum, defined since 1983).